#include "des_more.h"

//#pragma GCC push_options
//#pragma GCC optimize ("unroll-loops")

// Permuted Choice 1 Table [7*8]
static const char PC1[] =
{
	57, 49, 41, 33, 25, 17,  9,
	1, 58, 50, 42, 34, 26, 18,
	10,  2, 59, 51, 43, 35, 27,
	19, 11,  3, 60, 52, 44, 36,

	63, 55, 47, 39, 31, 23, 15,
	7, 62, 54, 46, 38, 30, 22,
	14,  6, 61, 53, 45, 37, 29,
	21, 13,  5, 28, 20, 12,  4
};

// Permuted Choice 2 Table [6*8]
static const char PC2[] =
{
	14, 17, 11, 24,  1,  5,
	3, 28, 15,  6, 21, 10,
	23, 19, 12,  4, 26,  8,
	16,  7, 27, 20, 13,  2,
	41, 52, 31, 37, 47, 55,
	30, 40, 51, 45, 33, 48,
	44, 49, 39, 56, 34, 53,
	46, 42, 50, 36, 29, 32
};

// Iteration Shift Array
static const char ITERATION_SHIFT[] =
{
	//  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16
	1,  1,  2,  2,  2,  2,  2,  2,  1,  2,  2,  2,  2,  2,  2,  1
};

#define LB32_MASK 0x00000001
#define LB64_MASK 0x0000000000000001
#define L64_MASK  0x00000000ffffffff

// Initial Permutation Table [8*8]
static const char IP[] =
{
	58, 50, 42, 34, 26, 18, 10, 2,
	60, 52, 44, 36, 28, 20, 12, 4,
	62, 54, 46, 38, 30, 22, 14, 6,
	64, 56, 48, 40, 32, 24, 16, 8,
	57, 49, 41, 33, 25, 17,  9, 1,
	59, 51, 43, 35, 27, 19, 11, 3,
	61, 53, 45, 37, 29, 21, 13, 5,
	63, 55, 47, 39, 31, 23, 15, 7
};

// Inverse Initial Permutation Table [8*8]
static const char FP[] =
{
	40, 8, 48, 16, 56, 24, 64, 32,
	39, 7, 47, 15, 55, 23, 63, 31,
	38, 6, 46, 14, 54, 22, 62, 30,
	37, 5, 45, 13, 53, 21, 61, 29,
	36, 4, 44, 12, 52, 20, 60, 28,
	35, 3, 43, 11, 51, 19, 59, 27,
	34, 2, 42, 10, 50, 18, 58, 26,
	33, 1, 41,  9, 49, 17, 57, 25
};

// Expansion table [6*8]
static const char EXPANSION[] =
{
	32,  1,  2,  3,  4,  5,
	4,  5,  6,  7,  8,  9,
	8,  9, 10, 11, 12, 13,
	12, 13, 14, 15, 16, 17,
	16, 17, 18, 19, 20, 21,
	20, 21, 22, 23, 24, 25,
	24, 25, 26, 27, 28, 29,
	28, 29, 30, 31, 32,  1
};

// The S-Box tables [8*16*4]
static const char SBOX[8][64] =
{
	{
		// S1
		14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
		0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
		4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
		15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13
	},
	{
		// S2
		15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
		3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
		0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
		13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9
	},
	{
		// S3
		10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
		13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
		13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
		1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12
	},
	{
		// S4
		7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
		13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
		10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
		3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14
	},
	{
		// S5
		2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
		14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
		4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
		11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3
	},
	{
		// S6
		12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
		10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
		9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
		4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13
	},
	{
		// S7
		4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
		13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
		1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
		6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12
	},
	{
		// S8
		13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
		1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
		7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
		2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11
	}
};

// Post S-Box permutation [4*8]
static const char PBOX[] =
{
	16,  7, 20, 21,
	29, 12, 28, 17,
	1, 15, 23, 26,
	5, 18, 31, 10,
	2,  8, 24, 14,
	32, 27,  3,  9,
	19, 13, 30,  6,
	22, 11,  4, 25
};

DES::DES(ui64 key)
{
	keygen(key);
}

ui64 DES::encrypt(ui64 block)
{
	return des(block, false);
}

ui64 DES::decrypt(ui64 block)
{
	return des(block, true);
}

ui64 DES::encrypt(ui64 block, ui64 key)
{
	DES des(key);
	return des.des(block, false);
}

ui64 DES::decrypt(ui64 block, ui64 key)
{
	DES des(key);
	return des.des(block, true);
}

void DES::keygen(ui64 key)
{
	// initial key schedule calculation
	ui64 permuted_choice_1 = 0; // 56 bits
	for (ui8 i = 0; i < 56; i++)
	{
		permuted_choice_1 <<= 1;
		permuted_choice_1 |= (key >> (64 - PC1[i])) & LB64_MASK;
	}

	// 28 bits
	ui32 C = (ui32)((permuted_choice_1 >> 28) & 0x000000000fffffff);
	ui32 D = (ui32)(permuted_choice_1 & 0x000000000fffffff);

	// Calculation of the 16 keys
	for (ui8 i = 0; i < 16; i++)
	{
		// key schedule, shifting Ci and Di
		for (ui8 j = 0; j < ITERATION_SHIFT[i]; j++)
		{
			C = (0x0fffffff & (C << 1)) | (0x00000001 & (C >> 27));
			D = (0x0fffffff & (D << 1)) | (0x00000001 & (D >> 27));
		}

		ui64 permuted_choice_2 = (((ui64)C) << 28) | (ui64)D;

		sub_key[i] = 0; // 48 bits (2*24)
		for (ui8 j = 0; j < 48; j++)
		{
			sub_key[i] <<= 1;
			sub_key[i] |= (permuted_choice_2 >> (56 - PC2[j])) & LB64_MASK;
		}
	}
}

ui64 DES::des(ui64 block, bool mode)
{
	// applying initial permutation
	block = ip(block);

	// dividing T' into two 32-bit parts
	ui32 L = (ui32)(block >> 32) & L64_MASK;
	ui32 R = (ui32)(block & L64_MASK);

	// 16 rounds
	for (ui8 i = 0; i < 16; i++)
	{
		ui32 F = mode ? f(R, sub_key[15 - i]) : f(R, sub_key[i]);
		feistel(L, R, F);
	}

	// swapping the two parts
	block = (((ui64)R) << 32) | (ui64)L;
	// applying final permutation
	return fp(block);
}

ui64 DES::ip(ui64 block)
{
	// initial permutation
	ui64 result = 0;
	for (ui8 i = 0; i < 64; i++)
	{
		result <<= 1;
		result |= (block >> (64 - IP[i])) & LB64_MASK;
	}
	return result;
}

ui64 DES::fp(ui64 block)
{
	// inverse initial permutation
	ui64 result = 0;
	for (ui8 i = 0; i < 64; i++)
	{
		result <<= 1;
		result |= (block >> (64 - FP[i])) & LB64_MASK;
	}
	return result;
}

void DES::feistel(ui32 &L, ui32 &R, ui32 F)
{
	ui32 temp = R;
	R = L ^ F;
	L = temp;
}

ui32 DES::f(ui32 R, ui64 k) // f(R,k) function
{
	// applying expansion permutation and returning 48-bit data
	ui64 s_input = 0;
	for (ui8 i = 0; i < 48; i++)
	{
		s_input <<= 1;
		s_input |= (ui64)((R >> (32 - EXPANSION[i])) & LB32_MASK);
	}

	// XORing expanded Ri with Ki, the round key
	s_input = s_input ^ k;

	// applying S-Boxes function and returning 32-bit data
	ui32 s_output = 0;
	for (ui8 i = 0; i < 8; i++)
	{
		// Outer bits
		char row = (char)((s_input & (0x0000840000000000 >> 6 * i)) >> (42 - 6 * i));
		row = (row >> 4) | (row & 0x01);

		// Middle 4 bits of input
		char column = (char)((s_input & (0x0000780000000000 >> 6 * i)) >> (43 - 6 * i));

		s_output <<= 4;
		s_output |= (ui32)(SBOX[i][16 * row + column] & 0x0f);
	}

	// applying the round permutation
	ui32 f_result = 0;
	for (ui8 i = 0; i < 32; i++)
	{
		f_result <<= 1;
		f_result |= (s_output >> (32 - PBOX[i])) & LB32_MASK;
	}

	return f_result;
}

DESCBC::DESCBC(ui64 key, ui64 iv) :
	des(key),
	iv(iv),
	last_block(iv)
{
}

ui64 DESCBC::encrypt(ui64 block)
{
	last_block = des.encrypt(block ^ last_block);
	return last_block;
}

ui64 DESCBC::decrypt(ui64 block)
{
	ui64 result = des.decrypt(block) ^ last_block;
	last_block = block;
	return result;
}

void DESCBC::reset()
{
	last_block = iv;
}